This application claims the priority benefit of Taiwan application Serial No. 89126545, filed on Dec. 13, 2000.
1. Field of Invention
The present invention relates to formation of liquid crystal display. More particularly, the present invention relates to a method for forming a multi-gap liquid crystal display.
2. Description of Related Art
Display is a very common device in our daily life. For example, a TV set or a computer system always need a display, whereby images can be shown on the screen, and present to the user. If the display is designed using technology of cathode-ray tube (CRT), it usually needs a large space, causing inconvenient. Especially, the notebook computer system cannot be equipped with the CRT display. Therefore, a planar display with image pixel design, such as a thin film transistor liquid crystal display (TFT LCD), has been successfully developed.
The liquid crystal display is designed with a mechanism of non-spontaneous emitting light. Liquid crystal is a material has state between crystal and liquid phase. When the liquid crystal cells are applied with external electric field, aligned direction of liquid crystal cells then changes due to the affection of the electric field. The direction of the liquid crystal then results in a change of polarization for the passing light. In associating with a polarizing plate, The liquid crystal can behave like an optical gate, and thereby the mechanism can be used to form a displaying device. However, the transmission rate may vary with different wavelengths and different viewing angles. This phenomena cause issues, such as color shift and dispersion. These issues are strongly necessary to be solved.
The invention provides a method for forming a multi-gap liquid crystal display. The method includes providing a substrate. A first insulating layer is formed on the substrate. Several bus lines are formed on the first insulating layer. A second insulating layer is formed on the first insulating layer and the bus lines. The bus lines divides the substrate into a first color region, a second color region, and a third color region. A photoresist layer covers the second color region and the third color region, where the thickness of the photoresist layer at the second color region is less than the thickness at the third color region. A portion of the first insulating layer and the second insulating layer is etched to expose the substrate at the first color region. A portion of the photoresist layer at the second color region is further removed, whereby the second insulating layer is exposed and a remaining portion of the photoresist layer still covers the third color region and the bus lines. The second insulating layer is etched to expose the first insulating at the second color region, using the remaining portion of the photoresist layer as an etching mask. Alternatively, in the foregoing first step of etching can only remove a portion or the whole of the second insulating layer in the first color region, and then the second step of etching removes the first insulating layer to expose the substrate. However, a portion of the first insulating layer can optionally remain without exposing the substrate at the first color region. The purpose of the etching is to have three different thickness, so as to respectively have different xcex94nd for the insulating layer.
In the foregoing, the photoresist layer with different thickness can be formed by technology of phase shift photomask, so that it has different thickness at the different color regions. The photoresist layer has two patterns and therefore one photolithographic process can be saved in the fabrication process. The fabrication cost and time can be effectively reduced.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.